Use mojo SystemTray interfaces for both mash and classic ash

ash/common/system/tray/system_tray_delegate.h

Index: ash/common/system/tray/system_tray_delegate.h
diff --git a/ash/common/system/tray/system_tray_delegate.h b/ash/common/system/tray/system_tray_delegate.h
index 9ec8238f508bdfba076488d0b6bbe1df7375048c..df316aeb96764816c4f31c0f49f4cf1be5579f60 100644
--- a/ash/common/system/tray/system_tray_delegate.h
+++ b/ash/common/system/tray/system_tray_delegate.h
@@ -144,18 +144,12 @@ class ASH_EXPORT SystemTrayDelegate {
   // Fills |info| structure (which must not be null) with current update info.
   virtual void GetSystemUpdateInfo(UpdateInfo* info) const;
 
-  // Returns the desired hour clock type.
-  virtual base::HourClockType GetHourClockType() const;
-
   // Shows settings.
   virtual void ShowSettings();
 
   // Returns true if settings menu item should appear.
   virtual bool ShouldShowSettings();
 
-  // Shows the settings related to date, timezone etc.
-  virtual void ShowDateSettings();
-
   // Shows the dialog to set system time, date, and timezone.
   virtual void ShowSetTimeDialog();